A variety of devices maintained by a user, such as laptop computers, smart phones, and personal digital assistants (PDAs), can operate to communicate with other devices using applications, such as email and Instant Messenger (IM) applications. The information may be transmitted to and received from the other devices using addresses identified in a contact list. While some development effort has been focused on various ways of adjusting membership in a user's contact list, this capability does not take full advantage of various aspects of the user's behavior that can be used to increase user productivity.